EPA-600/2-76-245
September 1976
Environmental Protection Technology Series
EMOVAL AND SEPARATION OF
SPILLED HAZARDOUS MATERIALS FROM
IMPOUNDMENT BOTTOMS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2/76-245
September 1976
REMOVAL AND SEPARATION OF
SPILLED HAZARDOUS MATERIALS
FROM IMPOUNDMENT BOTTOMS
by
Michael A. Nawrocki
Hittman Associates, Inc.
Columbia, Maryland 21045
Contract No. 68-03-0304
Project Officer
John E. Brugger
Oil and Hazardous Materials Spills Branch
Industrial Environmental Research Laboratory - Cincinnati
Edison, New Jersey 08817
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental Research
Laboratory - Cincinnati, U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of the U.S. Environmental
Protection Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
11
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FOREWORD
When energy and material resources are extracted, processed, converted,
and used, the related pollutional impacts on our environment and even on
our health often require that new and increasingly more efficient pollution
control methods be used. The Industrial Environmental Research Laboratory -
Cincinnati (lERL-Ci) assists in developing and demonstrating new and improved
methodologies that will meet these needs both efficiently and economically.
A full-scale system has been evaluated for safely removing and process-
ing hazardous materials from pond bottoms. A spilled hazardous material
that has settled to the bottom of an impoundment poses immediate safety and
health hazards to the public and to the environment and, further, continues
to present a danger and to degrade the environment until it is removed
and properly disposed of. Those concerned with the cleanup of spills and
with environmental restoration,'as well as public health and safety officials,
will find useful information in this report. Further information may be
obtained by contacting the Oil and Hazardous Materials Spills Branch of
lERL-Ci at Edison, New Jersey 08817.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
ill
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ABSTRACT
A demonstration was conducted of a system for removing spilled hazardous
materials from pond bottoms and separating the hazardous materials and
suspended solids from the resulting dredged slurry. The removal system
consisted of a MUD CAT dredge, which can pump a discharge of approximately
1500 gallons per minute with a solids concentration of 10 to 30 percent.
The processing system—in order of processing of material--consisted of a
pair of elevated clarifier bins placed in series, a bank of six 4-inch
diameter hydrocyclone cones, a conventional cartridge filter unit, and a
newly developed Uni-Flow bag-type fabric filter.
Four different simulated hazardous materials were placed on the pond bottom,
namely, very fine iron powder, fine glass beads, iron filings, and coal.
These materials were then removed from the pond bottom by the MUD CAT dredge
and pumped through the processing system. Tests were conducted to determine
the efficiency of removal of these materials from the pond bottom by the
dredge and also the efficiency of the processing system in removing these
simulated hazardous materials from the dredged slurry. Using latex paint, a
test was also conducted on the efficiency of the processing system in
removing a real hazardous material from dredged slurry.
The MUD CAT dredge was very efficient in removing the simulated hazardous
material from the pond bottom, averaging 99.3 percent removal for the four
materials tested. Similarly, the overall processing system removed
essentially all of the glass beads, iron filings, and coal, and 99.9 percent
of the iron powder from the dredged slurry. During processing of the latex
paint, 95.5 percent of the pigment was removed by the system.
After the field demonstration, evaluations and investigations were conducted
on the tested apparatus, as well as on.other equipment that could be used
in a full 1500-gallons-per-minute portable processing system. A system
consisting of a portable scalping-classifying tank combined with spiral
classifiers, a Uni-Flow filter, and an inclined tube settler was conceptu-
alized and preliminarily analyzed.
This report was submitted in fulfillment of EPA Contract Number 68-03-0304
by Hittman Associates, Inc. Work was completed as of October 31, 1974.
iv
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CONTENTS
Foreword 111
Abstract 1v
List of Figures vi
List of Tables v11
Acknowledgments v111
Sections
I Introduction 1
II Conclusions 3
III Recommendations 5
IV Field Demonstration Description 6
V Results 20
VI Discussion of Field Results 31
VII Conceptual Portable System 37
VIII References 53
Appendices
A Illustrations of Removal and Processing Equipment 54
B Detailed Data and Computations 58
C Alternative Equipment 65
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LIST OF FIGURES
Number Page
1 Schematic of Processing and
Sludge Disposal System 9
2 Plan View of Simulated Hazardous
Materials Test Area and Sampling
Points on POnd Bottom 14
3 Schematic of Conceptual System 39
4 Portable Seal ping-Classifying
Tank Combined with Spiral
Classifiers 41
5 Hypothetical Grain Size Distribu-
tion of Dredged Sediment 45
6 Plan View of Uni-Flow Filter for
Conceptual Systems 48
7 Portable Scalper and Classifier
Costs 51
VI
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LIST OF TABLES
Number Page
1 Characteristics of Simulated Hazardous
Materials 10
2 Results of Simulated Dredge Pump Failure
Test 21
3 Removal of Simulated Hazardous Materials
from Pond Bottom 23
4 Confidence Levels of Bottom Sampling Tests.. 24
5 Composite Dredged Slurry Concentrations 26
6 Summary of System Component Removal of
Simulated Hazardous Material 27
7 Simulated Hazardous Materials Balance 29
8 Results of Processing Latex Paint 30
9 Mass Balance of Initial Separation Phase 46
10 Estimated Initial Cost of 1500 gpm Portable
Separation System 50
vii
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ACKNOWLEDGMENTS
The support and technical guidance received from Dr. John E. Brugger,
serving as Project Officer for the U.S. Environmental Protection Agency,
is greatly appreciated. His guidance, timely suggestions, and technical
expertise, especially in the area of hazardous materials spills and
containment, were especially helpful. The technical assistance provided
by Mr. Paul Heitzenrater and Mr. J.J. Mulhern of the U.S. EPA's Office
of Research and Development is gratefully acknowledged.
The field demonstration of the dredging and processing of the simulated
hazardous materials was done in cooperation with the Prince George's County,
Maryland, Department of Public Works. They allowed unrestricted use of
their sediment pond for dredging operations and the surrounding land for the
processing.
viii
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SECTION I
INTRODUCTION
Practical methods for the removal and processing of hazardous
or semihazardous materials from the bottoms of water bodies
are receiving relatively high priority as targets for envi-
ronmental action. Not only must the offending material be
removed from the bottom sediments in an efficient and safe
manner, but the removed sediment and hazardous material
mixture must also be processed and disposed of in an envi-
ronmentally acceptable and safe manner.
Consequently, Hittman Associates, Inc., under contract to the
U.S. Environmental Protection Agency, conducted a demon-
stration of a system for the^removal and processing of
hazardous and semihazardous materials from the bottom of
a shallow pond. Since it is difficult to justify the spilling
of real hazardous materials into an aquatic environment even
under research conditions, a number of simulated hazardous
materials were spilled onto a pond bottom for the removal
and processing demonstration. These simulated hazardous
materials were relatively innocuous substances whose phys-
ical properties were chosen to represent a range of prop-
erties which might be displayed by real hazardous materials.
The purpose of the demonstration project was twofold. The
first was to demonstrate a technique for removing hazardous
materials from bottoms of water bodies at a high rate and yet
have minimal adverse effects on the surrounding water body.
The second purpose of the program was to evaluate a portable
system which could be set up to process the sediment and
hazardous materials mixture and return clean water to the
pond.
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The removal and processing systems used for this demon-
stration were the same as used on a previous EPA contract
(Ref. 1) which demonstrated the dredging and processing of
plain sediments. The removal system used was a MUD CAT
dredge manufactured by National Car Rental System, Inc.
It is specially designed for use on small bodies of water,
and to impart minimum turbidity to the water while dredging.
It can discharge approximately 1500 gallons per minute (gpm)
of slurry with a solids concentration of 10 to 30 percent.
Processing was performed by a system consisting of a pair
of elevated settling bins, a bank of hydrocyclones, a
standard cartridge-type water filter unit, and a bag-type
filter known as a Uni-Flow filter. Basically, the Uni-
Flow filter consists of a number of hanging hoses. Dirty
water is pumped into the inside of the hoses and is allowed
to filter through them. The suspended matter is trapped
on the inside of the hoses. Periodically, the collected
sludge is flushed from the inside of the hoses.
Each piece of equipment was evaluated as to its ability
to remove the simulated hazardous materials along with
the dredged solids. A conceptual design of a portable
processing system was prepared based on the results of
the field demonstration and additional manufacturer's
1i terature.
This report constitutes the final report on the entire
project. It includes the results of the field trials
of the processing system, the evaluation of sediment
processing equipment, and a conceptual design of a port-
able system for removing and processing hazardous ma-
terials from water bodies.
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SECTION II
CONCLUSIONS
The MUD CAT dredge is an effective method for removing
undesirable participate materials from pond bottoms. How-
ever, it can be expected that up to one foot of bottom sedi-
ments will be removed along with the undesirable material,
since it is difficult to regulate the depth of cut to less
than a few inches.
The portable separation system which was field tested
consisted of two elevated clarifier bins, hydrocyclones,
a cartridge filter unit, and a Uni-Flow bag-type fabric
filter. It proved efficient in removing particulate
undesirable material along with the suspended solids present
in a dredged slurry. Through a test on latex paint, there
is also an indication that the system is applicable to re-
moving some components of liquid hazardous materials present
in dredged slurries.
Of the system elements downstream of the elevated bins, the
hydrocyclones consistently removed the greatest amount of
the particulate simulated hazardous material from the dredged
slurry. The overall quality of the effluent from the process-
ing system was adversely affected by leaks in the Uni-Flow
hoses, which allowed unfiltered water to enter the effluent.
During the processing of latex paint, the hydrocyclones
removed none of- the pigment from the process stream. The
Uni-Flow filter was the most effective component of the
processing system in removing the paint pigment from the
processing stream.
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A portable hazardous materials removal and separation
system similar to the conceptual system presented herein can
be designed and assembled to operate at a throughput flow
rate of 1500 gallons per minute. Such a system would require
five semitrailer trucks to transport the entire system.
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SECTION III
RECOMMENDATIONS
It is recommended that the MUD CAT dredge or its equivalent
be utilized for the removal of particulate hazardous ma-
terials from water bodies when high flow rates and/or rapid
removal is desired, since it produces a minimum resuspension
of the dredged material into the surrounding water body.
Consideration should be given to the construction of a
portable processing system similar to the conceptual system
presented (consisting of a scapling-classifying tank com-
bined with spiral classifiers, a Uni-Flow filter, and an
inclined tube settler) if there is a continued projected
need for a high-flow-rate hazardous materials processing
system. Before finalization of design of such a system,
field evaluations should be performed on the system com-
ponents to ensure their working as projected at the full
1500-gal Ions-per-minute flow rate.
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SECTION IV
FIELD DEMONSTRATION DESCRIPTION
REMOVAL SYSTEM
The system utilized for removing the spilled simulated
hazardous materials from the pond bottom was an approximately
30-foot-long MUD CAT dredge manufactured by National Car
Rental System, Inc., MUD CAT Division. The dredge moves
in straight-line directions by winching itself along a
taut, fixed cable. Bottom sediment removal equipment on
the dredge consists of an eight-foot-long, horizontally-
opposed, adjustable depth, power-driven auger and a pump
rated at about 1500 gpm with a 10 to 30 percent solids
concentration of the dredged slurry. A retractable mud
shield over the auger minimizes mixing of the disturbed
bottom deposits with the surrounding pond water. The
dredge also comes equipped with a rock box into which
objects greater than eight inches in diameter (the di-
ameter of the discharge line) are automatically discarded
before the dredged slurry is pumped into the discharge line.
Photographs of the MUD CAT dredge are contained in Appendix A
PROCESSING SYSTEM
The system used for processing the suspended sediment and
simulated hazardous material dredged slurry was set-up
on a 50-foot-high knoll, approximately 600 feet from the
edge of the pond. It included, in order of processing
of material:
1. Two steep-sided elevated bins, each with an
initial capacity of 36 cubic yards, installed
in series. They are of the type typically
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used in concrete batch plant operations. The
discharge from the dredge was Dumped directly
to the first bin where settling of suspended
solids occurred. The slurry was then allowed
to overflow into the second bin, where addi-
tional settling occurred. From the second
bin, the flow was split to either a temporary
holding/settling basin or the feed pump for
the secondary separation phase. Each of the
elevated bins provided about 144 square feet
of surface area for settling.
A bank of hydrocyclones manufactured by DEMCO
Incorporated, and consisting of six four-inch
style H cones with three-gallon silt pots, a
closed underflow header, and automatic solids
unloading.
A commercially available cartridge-type water
filter manufactured by Crall Products, Inc.
The unit consisted of four model 16-17-51
filters, operating in parallel, with an
automatic backflushing machanism. Each of
the filters contained 51 permanent sand car-
tridges with filter openings rated at 25
microns.
One Uni-Flow bag-type fabric filter consisting
of 720 one-inch diameter, 10-foot-long, woven
polypropylene hoses. The hoses were arranged
in six banks of 120 hoses each. This enabled
the shutting-down of one bank for hose main-
tenance or replacement while the other five
banks could be kept on-line. The slurry was
pumped into a top header which distributed
the influent to each bank of hoses. The fil-
trate from the hoses is collected in a bottom
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tray and allowed to flow by gravity back to
the pond. Normally, every 5-1/2 minutes the
sludge within the hoses is drained for 30
seconds into a collection trough and allowed
to flow by gravity into a sludge disposal basin.
Figure 1 is a schematic diagram of the overall processing and
sludge disposal system. Photographs of the various components
of the processing system are contained in Appendix A.
FIELD TESTS PERFORMED
Three separate types of tests were performed during the
field demonstration:
1. Tests to determine the extent of resuspension
of material into the water column during nor-
mal dredging and also during and after a sim-
ulated total failure of the MUD CAT prime
mover pump or blockage of the discharge line.
These conditions would cause the dredged
slurry already in the discharge line to flow
back into the pond.
2. Tests to determine the suitability of the
MUD CAT and dredged slurry processing system
for the removal and processing of hazardous
materials from a small pond. Simulated haz-
ardous materials were used during the tests
for the reasons noted in Section III. The
simulated hazardous materials used were very
fine iron powder, fine glass beads, iron
filings, and coal. Table 1 shows the phys-
ical characteristics of the simulated haz-
ardous materials and the amounts placed on
the pond bottom.
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MUD CAT discharge
approx. 1500 gpm
Initial Separation
Two 36-yard
Elevated Bins
Temporary Holding/
Settling Basin
Return Water
to pond
approx.
500 gpm
Secondary Separation
Hydrocyclones
Final Filtration
Cartridge Filter
Unit
Final Filtration
Uni-Flow Filter
trucking
backflush
backflush
backflush
Return Water
to pond
Bin Solids
Disposal Area
Sludge Disposal
Area
FIGURE 1. Schematic of Processing and Sludge Disposal System
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Table 1. CHARACTERISTICS OF SIMULATED
HAZARDOUS MATERIALS
Amount
Material (lb)
Iron
(S.G
Glas
(S.G
Iron
(S.G
Coal
(S.G
powder 800
.=5.04)
s beads 500
.=2.50)
filings 500
.=7.88)
500
.=1 .44)
Particle
size (microns)
420
250
105
75
250
105
75
2,000
420
250
105
75
3/4 in.
4,760
2,000
420
%
Finer
100.0
99.9
82.7
64.7
100.0
9.7
1.5
100.0
81 .2
42.2
9.5
5.1
71.4
8.1
0.8
0.5
Note: The "% Finer" column shows the percent of the material that
has a particle size equal to or smaller than the size indicated
in the adjacent "Particle size" column.
10
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3. A brief test to determine the efficiency of
the processing system in removing real haz-
ardous material from a dredged slurry. In
this test, a latex paint was dumped directly
into the influent to the processing system
and the amount of pigment removed by the proc-
essing system was determined.
FIELD TEST PROCEDURES
Simulation of Total Failure of the Dredge
The MUD CAT dredge was positioned in a location on the pond
such that turbidity imparted to the pond by the simulated
failure could disburse in an unimpeded manner to all areas
of the pond. The MUD CAT was operated at normal pump rate
( 1500 gpm ), rate of advance (10 feet per minute), and mud
shield position (up) for three minutes to ensure that the
discharge line was fully charged with dredged slurry that
was representative of normal operating conditions. The
MUD CAT operated in about four feet of water for the test.
After three minutes the MUD CAT' s prime mover was shut off,
simulating a total failure. The pump stopped, there was
no movement along the central cable, the auger ladder was
neither raised nor lowered, and the turbidity shield was
not moved.
Water sampling and photographic documentation were done
simultaneously. A two man sampling team worked from a
work boat and sampled at less than five feet from the
MUD CAT auger before dredging, at five and ten feet from
the MUD CAT auger during dredging, at five feet and ten
feet from the auger during the simulated failure, at four
foot intervals (composite sample) from zero to twenty feet
11
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from the auger immediately after the simulated failure, and
a final sample at twenty feet from the auger after the sim-
ulated failure. Laboratory tests were performed to deter-
mine total suspended solids concentration for all samples
collected. The photographers attempted to document any
turbidity, discoloration, or plume imparted to the pond
during the conducting of the simulated failure.
Removal and Processing of Simulated Hazardous Material
from a Pond Bottom
A test area eight feet wide and 28 feet long, with lead-
in and lead-out areas of four feet at each end, was pre-
pared on the pond bottom such that the center line of the
test area corresponded to the MUD CAT's positioning cable.
Marker poles were placed at the corners of the test area,
and the MUD CAT positioning cable over the test area was
marked at four-foot intervals to provide reference points
for bottom sampling. Each simulated hazardous material was
placed on the bottom of the test area in a uniformly dis-
tributed pattern using a 6-foot length of 6-inch diameter
P.V.C. pipe.
With the MUD CAT positioned well outside the test area,
pond water only was pumped into the bins until they were
full and the process system was balanced and backflushed.
During this pumping, the process system was charged with
clean pond water and all pressure controls were adjusted
to proper balance. The auger of the MUD CAT was lowered
to the pond bottom as it reached the lead-in area at a rate
of ten feet per minute. After all dredge operations were
stabilized during the traverse of the lead-in area, the
test area was traversed in a smooth and continuous manner
under normal operating parameters. Auger rotation was
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stopped after the complete traverse of the test area and
lead-out area and pond water only was pumped in order to
clear the dredge discharge line of all simulated hazardous
material. During this time the dredge advanced to a posi-
tion remote from the test area.
A survey of the pond bottom was conducted before and after
each simulated hazardous material test to determine the
amount of pond bottom material removed by the MUD CAT during
each test. A La Motte Chemical Co. Code 1061 Bottom Sam-
pling Dredge was used to collect samples of the bottom after
each simulated hazardous material removal test. The bottom
sampling pattern was on alternate, four-foot centers begin-
ing two feet inside the test area. Figure 2 shows this
sampling pattern. Thus, a total of seven bottom samples
were collected after each simulated hazardous material
removal test, except for the first test using fine iron
powder, when each four-foot square area was sampled and
a total of 14 samples were collected.
The process system was balanced and backflushed during the
initial pumping of the pond water only. All process system
components were operated without backflushing during the
conduct of the test. The two minute test run time was less
than the time between normal automatic backflushing cycles.
Effluent sampling was accomplished as follows:
(1) MUD CAT discharge: One composite sample, con-
sisting of small, discrete samples collected
at ten-second intervals, was collected over
a two minute time period which began one
minute after sediment was first observed in
the discharge line.
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T
±
28'
Lead-in/lead-out area
-Test area centerline
Lead-in/lead-out area
• = normal bottom sampling locations
FIGURE 2. Plan View of Simulated Hazardous
Materials Test Area and Sampling Points
on Pond Bottom
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(2) Elevated bin discharge: The procedure for
sampling was the same as for the MUD CAT dis-
charge except that sampling was started at
one and one-half minutes after the start of
sample collection at the MUD CAT discharge.
(3) Hydrocyclone unit: Same as bin discharge.
(4) Cartridge filter: Same as bin discharge.
(5) Uni-Flow filter: Procedure was the same as
the preceding except that the first sample
was taken thirty seconds after collection of
the first sample from the cartridge filter
unit, that is, two minutes after the start
of sampling at the MUD CAT discharge.
After the test, sludge sampling was accomplished as follows:
(1) Elevated bins: All water was decanted from
the bins. Core samples were taken at several
locations across the sediment, and one com-
posite sample was prepared for each bin.
(2) Hydrocyclone unit: One sample of material
ejected from the sludge pots just at the
start of backflushing was obtained.
(3) Cartridge filter unit: One composite sam-
ple of all four filters' backflush material
was collected.
(4) Uni-Flow: One sample of material ejected
from the sludge collecting chambers just
at the start of backflushing was obtained.
Laboratory tests were performed to determine total suspended
and dissolved solids for all samples collected.
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Processing of Latex Paint
The MUD CAT was operated at normal conditions for providing
dredged slurry to the process system except that the pumping
rate was reduced to 500 gallons per minute. To ensure that
no hazardous material was introduced into the temporary
holding basin, the overflow from the second bin was blocked
and all flow was diverted through the processing system.
After the bins were full, the processing system was balanced
as dredged slurry was pumped through it. Backflushing was
performed manually on all system components to clear them.
Hazardous material (latex paint) was then introduced directly
into the first bin into the dredge discharge plume at a
uniform rate. No backflushing was performed during the
processing of hazardous material; the time for the test
was less than the time for a normal backflushing cycle.
Sampling of effluent and sludge was the same as for the
tests using simulated hazardous materials. Laboratory tests
were performed to determine total suspended solids, and dis-
solved and adsorbed pigment for all samples collected.
LABORATORY ANALYSES
Analysis for the amount of suspended solids in the pond
water during the simulated dredge pump failure test and
in the effluents of the elements of the processing system
was performed in accordance with Standard Methods for the
Examination of Water and Vlastewater(Ref. 2).
The concentrations of simulated hazardous material in the
effluents of the system elements and remaining on the pond
bottom after dredging were determined by three methods:
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(1) Iron Powder and Iron Filings: These materials
were separated from soil particles magnetically.
Two grams of thoroughly blended dry sample were
placed in a petri dish and covered with a glass
cover. A seven and one-half pound horseshoe
magnet was placed on the covered petri dish.
The petri dish was then agitated. The iron
particles were trapped on the inside of the
glass cover during the agitation. The glass
cover and magnet were removed carefully so
that iron particles remained trapped on the
inside of the glass cover. The iron particles
were removed and the separation process was
continued until no iron particles were found
trapped on the inside of the glass cover. The
petri dish and soil was then weighed. The dif-
ference between the weight of the petri dish
and two gram soil sample before the removal of
iron particles and the weight of the petri
dish and soil after the removal of iron par-
ticles was taken as the weight of iron par-
ticles for a two gram sample. From this re-
sult, the percent of iron powder or iron
filings by weight in the sample was calculated.
(2) Coal: It was possible to separate the coal
particles from the dry soil sample from the
MUD CAT effluent by hand. The weight of coal
compared to the total weight of the dry sample
yielded the percent of coal, by weight, in
the sample. For the remaining effluents of
the processing system, a different approach
was used. The coal from the MUD CAT discharge
sample was pulverized. It was then blended
back into the dry material 1n the sample. A
17
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small sample of this blend was removed and placed
In a glass petri dish for microscopic examination
This MUD CAT discharge sample was then used as
the test sample. By comparing the known amount
of pulverized coal in this test sample to the
amounts found upon microscopic examination of
samples of the other effluents, the percent
of coal in the samples was estimated. For ex-
ample, since the amount of coal in the test
sample was 4.2 percent by weight, a sample
which exhibited one-fourth as much coal upon
microscopic examination was determined to
have approximately a 1.0 percent concentration
of coal .
(3) Glass beads: Microscopic examination was also
employed in the determination of the concen-
trations of glass beads in the system effluent
samples. A grid of 144 squares was affixed
to the glass petri dish. A small portion of
glass beads was placed in the petri dish and
weighed. Using the 144 square grid as a refer-
ence, the total number of glass beads was
counted under microscopic observation by sum-
ming the number of beads observed and counted
in each square. This process was repeated
several times, and an average weight per glass
bead was obtained. This value was applied to
the number of glass beads subsequently observed
and counted in measured portions of the efflu-
ent samples. From this, the concentrations of
glass beads in each sample was determined.
The hazardous material tested, latex paint, was analyzed
by analyzing the concentrations of calcium carbonate (CaCOS)
18
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both in solution and adsorbed to the sand and silt particles
in each sample. Calcium carbonate is one of the major con-
stituents of the pigment. The percentage of calcium car-
bonate in the pigment was given in the analysis of the
paint on the paint containers. Using the percentage of
calcium carbonate in the pigment, the amount of calcium
carbonate occuring naturally in the pond waters, and the
percentage of calcium carbonate in the samples collected,
the amount of pigment in the effluent of each element was
determined.
19
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SECTION V
RESULTS
SIMULATED DREDGE PUMP FAILURE
The results of the simulated dredge pump failure test are
shown in Table 2. During normal dredging, the plume of
suspended material imparted to the pond was observed to be
confined to within 15 to 20 feet from the dredge. At 20
feet from the auger of the dredge, the concentration of
suspended solids in the pond water fell to within the range
normally present in the pond.
During the simulated failure, the plume of suspended ma-
terial imparted to the pond was observed to stay within
about 25 feet from the dredge. Concentrations of suspended
solids within this 25-foot radius were, in some places, over
ten times the concentrations found during normal dredging.
Even though more suspended solids were imparted to the pond
during the simulated failure test than during normal dredging
they were observed to be confined to within the approximate
same distance from the dredge as during normal dredging.
Immediately after backflow from the simulated failure test
ended, the concentration of suspended solids fell off rapidly
with distance from the dredge auger. Within a few minutes,
the turbidity was observed to approach that normally present
in the pond.
REMOVAL OF SIMULATED HAZARDOUS MATERIALS FROM POND BOTTOM
Throughout these tests, the primary objective was to remove
as much of the simulated hazardous material from the pond
20
-------
Table 2. RESULTS OF SIMULATED
DREDGE PUMP FAILURE TEST
Suspended
Distance from Depth from Solids
MUD CAT Auger Surface Concentration
Condition (ft) (ft) (mg/1)
Before Dredging
(normal pond)
During Normal
Dredging
During Simulated
Fail ure
After Simulated
Failure (backflow
complete)
5
5
5
5
5
5
10
10
20
5
5
10
10
20
composi te:
0 to 20 ft
1
3
5
7
1
5
1
5
1
1
5
1
5
1
1
39
50
64
523
88
179
54
86
39
900
1260
648
175
89
226
21
-------
bottom as possible while operating at the normal pumping
and advance rates for the MUD CAT dredge. A secondary
consideration was to remove as little as possible of the
sediments from the pond bottom while picking up the simu-
lated hazardous material. One pass over the test area by
the dredge was usually sufficient to remove essentially all
of the simulated hazardous materials, except during the
glass beads test, when two passes were made over the test
area. Table 3 presents the results of the removal of the
simulated hazardous materials from the pond bottom. The
variability in the thickness of sediment removed for the
different tests reflects the inability of the dredge oper-
ators to determine precisely the depth to the pond bottom in
the very soft sediments present in the test area.
A statistical analysis was performed on the results obtained
from the bottom sampling tests after each simulated hazardous
material removal test. This analysis gives an indication of
the degree of reliability of the bottom sampling results.
Table 4 is a summary of the statistical tests. It indicates
that the number of bottom samples taken after each test was
adequate to predict the efficiency of removal of the simu-
lated hazardous materials by the MUD CAT dredge within an
acceptable range of error. In all cases, the total error
interval in the number of pounds predicted left on the bot-
tom of the pond through the sampling program is less than
one percent of the total weight of material placed on the
bottom.
During the dredging of the coal it was observed that very
fine particles of coal became suspended in the surrounding
pond water. This was probably due to the action of the
auger on the MUD CAT dredge causing the breaking up of the
22
-------
ro
co
Table 3. REMOVAL OF SIMULATED HAZARDOUS
MATERIALS FROM POND BOTTOM
Material
Iron Powder
Glass Beads
Iron Filings
Coal
Amount Placed
on Bottom
(lb)
800
500
500
500
Amount
Remaining
on Bottom
(lb)
8.0
<0.1
0.4
2.1
X
Removed
99.0
99.9+
99.9
99.6
Average Thickness
of Sediment
Removed
(ft)
1.12
0.61
0.22
1.14
No
1
2
1
1
. of Passes
by
Dredqe
(forward)
(forward &
backward)
(backward)
(backward)
-------
Table 4. CONFIDENCE LEVELS
OF BOTTOM SAMPLING TESTS
ro
Test
Iron
Coal
Glass
Iron
Material
Powder
Beads
Filings
Number
of
Samples
14
7
7
7
Predicted
Amount
Removed
(lb)
792.0
>499.9
499.6
497.9
Total Sampling
Error over Entire
Test Area
(lb)
+. 6.0
+ 1.5
+ 1.0
+ 1.0
Confidence
Level
90
90
99.9
99.9
-------
larger lumps of coal into smaller particles and the sub-
sequent suspension of these particles in the pond water.
These very fine particles remained in suspension for a long
time and settled back to the bottom, both within and out-
side the test area, within about one day after the test
was complete. Although the total weight of the suspended
coal was very small, it did give a black color to the pond
sediments up to a distance of approximately 20 feet from
the edge of the test area. No similar problems were ob-
served with the other simulated hazardous materials tested.
REMOVAL OF SIMULATED HAZARDOUS MATERIALS BY PROCESSING SYSTEM
Table 5 summarizes the composite dredged slurry concentrations
at each sampling point in the processing system for the four
simulated hazardous materials tested. It gives an indication
of the efficiency of removal of suspended solids for the
various units in the processing system. As can be seen from
Table 5, the dredge discharged between 10 and 14 percent sol-
ids during the tests, which is within the normal range. Pro-
cessing system flow ranged between 100 and 300 gpm and was
restricted mainly by backpressure from the cartridge filter
unit and restriction of the flow through the Uni-Flow filter
hoses by the trapped sediment .
The amount of simulated hazardous material entering/leaving
each system component was also determined so that each com-
ponent of the system could be evaluated as to its ability to
remove the various test materials along with the normal sus-
pended solids. The main interest was in the processing sys-
tem units downstream from the elevated bins. Table 6 is a
summary of the removal efficiencies of the hydrocylcones,
cartridge filter unit, and Uni-Flow filter. Here, the three
25
-------
ro
Table 5. COMPOSITE DREDGED
SLURRY CONCENTRATIONS
Sampl ing
Point*
#1
#2
#3
#4
#5
System Flow
(gpm)
Total Suspended Solids Concentration (ma/1
Iron Powder
129,210
61 ,320
40,390
26,200
230
100
Glass Beads
107,560
87,560
31,400
22,740
570
100
Iron Filings
107,030
67,390
44,690
26,250
660
300
) - Test
Coal
138,020
55,830
49,480
34,680
520
250
*Sampling Point Key:
#1 = MUD CAT discharge into elevated bins
#2 = Bin effluent - Influent to hydrocyclones
#3 = Hydrocyclone effluent - Influent to cartridge filter unit
#4 = Cartridge filter effluent - Influent to Uni-Flow filter
#5 = Uni-Flow effluent (return water to pond)
-------
types of removal equipment can be compared on a step-by-step
basis in terms of their ability to remove the simulated
hazardous materials which remained in the dredged slurry
after passing through the clarifier bins.
Table 6. SUMMARY OF SYSTEM COMPONENT REMOVAL
OF SIMULATED HAZARDOUS MATERIAL^
Percent removal of simulated
hazardous materials reaching
the processing system after
the elevated bins
Component
Hydrocyclones
Cartridge filters
Uni -Flow
Return water
to pond
Iron
powder
42.9
22.0
35.0
0.1
100.0
Glass
beads
87.8
6.1
6.1
100.0
I ron
fil ings
83.8
7.5
8.7
100.0
Coal
55.2
29.9
14.9
100.0
The overall consideration of this program was to briefly
test the ability of the processing system>which was al-
ready set up to remove suspended solids from dredged ma-
terial, to also remove certain types of hazardous materials
along with the suspended solids. Time and budgetary con-
straints were such that it was impossible to accurately
establish the fate of all the dredged materials which were
trapped in or passed through the elevated settling bins.
The removal of hazardous materials by the closed portion
of the processing system, as given in Table 6, could be
measured quite easily to a high degree of accuracy. How-
ever, results from the total processing system analyses were
accurate enough to compute materials balances for the entire
removal and processing system, including the elevated bins,
27
-------
for two of the four simulated hazardous materials tests.
Materials balances based on a 100 gpm flow rate are
shown in Table 7. Materials balances shown in Table 7
for the iron powder and coal are estimated values based
on observations of the influent and effluent concentra-
tions. Appendix B contains additional data collected
and calculations performed during this study.
REMOVAL OF LATEX PAINT BY PROCESSING SYSTEM
Testing the ability of the processing system to remove a
real hazardous material, in this case latex paint, was
done after dredging of the simulated hazardous materials
was complete. Twenty-one gallons of paint were dumped
directly into the dredge discharge plume into the first
elevated bin. The paint was dumped within a two-minute
period as dredging of normal bottom sediments was
occurring at a reduced rate of 500 gpm. Samples were
collected throughout the processing system during the
dumping of the paint for an additional two minutes after-
ward. Table 8 presents the results of this processing of
latex paint.
28
-------
Table 7. SIMULATED HAZARDOUS MATERIALS BALANCE
ro
to
Test Material (Ib removed per 100
Unit
Elevated bins
Bypass
Hydrocyclones
Cartridge f i 1 ters
Uni-Flow
Glass
Beads
6.2
19.7
17.3
1 .2
1 .2
Iron
Fi 1 ings
28.9
2.7
2.2
0.2
0.2
Iron
Powder*
7.4**
4.9**
2.1
1 .1
1 .7
gpm)
Coal*
5.3**
2.7**
1 .5
0.8
0.4
* Because of inaccuracies in measuring the amount of iron powder and coal
in the bypass, and the fact that these two simulated hazardous materials
were nonuniformly distributed in the bin sediments, the values shown
for the pounds removed by the elevated bins and bypass may not reflect
the true values.
** Imputed value .
-------
Table 8. RESULTS OF PROCESSING
LATEX PAINT
CO
o
System Unit
Hydrocyclones
Cartridge filters
Urn" -Flow
Return water
to pond
Effluent
Suspended
Solids Concentration
(mq/1)
140,500
103,040
94,430
1 ,770
Absorbed
Pigment
Removed
(lb)
0.00
4.02
5.83
0.47
Pigment in
Solution
Removed
(lb)
-0.03*
0.00
0.03
0.00
Total
Pigment
Removed
(lb)
j
-0.03*
4.02
5.86
0.47
The negative sign indicates that,in the hydrocyclones,the net effect was
an increase in the pigment in solution. The source of pigment was that
pigment adsorbed to silt particles which was agitated into solution by
the action of the hydrocyclones.
-------
SECTION VI
DISCUSSION OF FIELD RESULTS
REMOVAL SYSTEM
It is evident that the MUD CAT dredge is a relatively
effective method for removing undesirable participate
materials from pond bottoms. It removed from 99 to over
99.9 percent of the material placed on the bottom within
the test area. During some of the tests, however, up to
approximately one foot of bottom sediments were removed
along with the simulated hazardous material. Even though
relatively brief tests were performed, the degree to which
the test materials were removed by the dredge was observed
to be influenced by two factors.
First is the fact that during a backward cut, the MUD CAT
dredge has a greater efficiency for removal of sediment,
and consequently, of spilled hazardous material, than
during a forward cut. This is due to the fact that during
a backward cut the mud shield is fully extended over the
cutting auger and helps to prevent the resuspension of any
bottom sediments into the surrounding water. This in-
fluence was first observed during the test for removal of
glass beads. As the dredge traversed the area in a forward
cut, the pond bottom was quickly sampled behind the dredge.
The samples revealed that a large amount of glass beads
had been left on the bottom. Therefore, the dredge traversed
the area again, but in a backward cutting mode. The
remaining tests were both performed using backward cuts
by the dredge and showed higher removals than the first
test when a forward cut was used (see Table 3). Secondly,
the specific gravity, and possibly, the relative softness
31
-------
of the material being picked-up was observed to influence
the removal efficiency. During the two tests which were
made with the same direction of cut, i.e., backward only,
the lighter and softer material (coal) was observed to
have a lower removal rate and also be dispersed into
the surrounding water body more easily than the heavier
and harder iron filings.
Overall, the MUD CAT performed very satisfactorily in re-
moving undesirable particulate matter which had a wide
range of specific gravities and particle size from a pond
bottom. It is probable, therefore, that such a removal
system would be satisfactory for the removal of most par-
ticulate hazardous materials spills which have settled to
the bottom of a water body. The bottom sediments would
have to be relatively soft to ensure a high percentage of
pick-up by the MUD CAT dredge. The minimum depth of cut
by the dredge into the pond bottom which produced efficient
removal of the test material was approximately 0.3 feet.
It has been postulated that the MUD CAT dredge could be
used somewhat as a floating pump platform to remove lighter
hazardous materials because the MUD CAT intake can be ele-
vated to the water surface. However, this is a relatively
inefficient means of removing floating or suspended hazard-
ous materials from a water body since large volumes of water
would also be pumped and have to be processed. However, the
MUD CAT might be used to divert small streams around a
spill site.
PROCESSING SYSTEM
The ability of the processing system to remove a variety of
undesirable particulate material along with suspended solids
from a dredged slurry and return a relatively high quality
32
-------
water to a pond was documented during the field demonstra-
tion. Essentially all of the glass beads, iron filings,
and coal, and 99.9 percent of the fine iron powder were
removed from the dredged slurry before the water was re-
turned to the pond.
Through the test on latex paint, there was also an indi-
cation that the system is applicable to removing some
components of liquid hazardous materials present in dredged
slurry. During this test, 95.5 percent of the pigment
reaching the system downstream of the clarifier bins was
removed along with the suspended solids. Leakage of the
Uni-Flow hoses prevented a greater removal efficiency, as
evidenced by the high suspended solids concentration shown
in Table 8.
The overall quality of the effluent from the processing
system was adversely affected by leaks in the Uni-Flow
hoses, which allowed unfiltered water to enter the ef-
fluent. This problem was also observed during previous
field tests of the system on dredged slurry (Ref. 1). During
the present tests, leakage was especially bad during the
testing of latex paint, when an overall effluent suspended
solids concentration of 1770 mg/1 was measured. When hose
failure is not a problem, the overall suspended solids con-
centration in the effluent can reasonably be expected to
be in the range of 100 to 300 mg/1 (Ref. 1).
Originally, the processing system was designed to be oper-
ated at a flow rate of 500 gpm. However, two conditions
were found to prevent operation at this optimum processing
rate. First, the backpressure in the cartridge filters, at
flow rates approaching 400 gpm and at the dredged slurry
33
-------
solids concentrations encountered, caused a reduction in
flow rate. Secondly, sediment rapidly builds up in the
Uni-Flow hoses. This buildup contributes to the back-
pressure in the system. Flow rates must be adjusted down-
ward to compensate for the increase in pressure on the hoses
in order to prevent their bursting. Expedient flow rates
for the Uni-Flow filter were found to be between 100 and
300 gallons per minute after the hoses had been coated by
sediment.
The elements in the processing system downstream of the ele-
vated bins operate as a closed system, the processing rate
of which is dependent upon the operating characteristics of
the most sensitive element. The Uni-Flow filter is the
most sensitive to pressure and therefore is the element in
the processing system upon which the total system is de-
pendent.
The hydrocyclone unit has a specified operating pressure
range in which removal of suspended solids is optimized.
This pressure range corresponds to a system flow rate of be-
tween 420 and 540 gpm. Therefore, the maximum flow rate of
approximately 300 gpm for the Uni-Flow filter after the
hoses become blocked with sediment limits the efficiency
of the hydrocyclone unit to a suboptimal range.
Efficiency of removal of the cartridge filters is not
significantly affected by changes in flow rate or pressure.
However, the cartridge filters can become the limiting ele-
ment in the processing system if the filter cartridges be-
come restricted by accumulated solids. When this happens
the cartridge filter unit governs the processing rate of
the system.
34
-------
During the processing of the simulated hazardous materials,
the hydrocyclones consistently removed the greatest amount
of simulated hazardous material which entered the processing
system after the bins. In three out of four tests, the llni-
Flow filter removed greater amounts of simulated hazardous
material than the cartridge filter unit, even though it was
downstream of the cartridge filters. After the test pro-
gram was complete, the cartridge filters were opened and
cracks were discovered in a number of the cartridges. These
cracks were postulated to have occurred during backflushing
of the filters and would allow unfiltered dredged slurry to
leak through this unit.
Very little pigment in the water base paint processed as
a hazardous material was found in solution in any of the
system effluents; practically all the pigment in the ef-
fluent samples was adsorbed to silt particles. In the
processing of the water base paint, the hydrocyclones re-
moved no pigment. In fact, the hydrocyclone unit resus-
pended some pigment that had entered it adsorbed to silt
particles, so that the unit made a negative contribution
to the removal system. The cartridge filter unit removed
no pigment from solution and removed less adsorbed pigment
than did the Uni-Flow filter. The Uni-Flow filter was the
only element in the system which removed pigment from solu-
tion.
The complete sediment processing system may not be
applicable in all situations. Some components of the
system are more suited for removing certain particle size
ranges and specific gravities, and thus in some instances
some of the components could possibly be eliminated. For
example, as evidenced by the results, the hydrocyclones are
most efficient in removing sand size or larger particles of
35
-------
relatively high specific gravity. If the undesirable ma-
terial is composed mainly of fines, little advantage will
be gained by processing the material through hydrocyclones.
This was especially evident during the latex paint test.
A degree of redundancy is provided in the system by utili-
zing both the cartridge filter unit and the Uni-Flow filter
in the final filtration step. Both of these filters are
not required for final filtration. From these tests with
simulated hazardous materials and previous experiments with
dredged slurries, the Uni-Flow filter proved to be more use-
ful in the processing system than the cartridge filter unit:
it can efficiently remove a variety of material with dif-
ferent particle sizes and specific gravities.
Sizing and selection of the individual components of the
processing system should ideally be performed on a case-
by-case basis. The clarifier bins, hydrocyclones, and Uni-
Flow filter are all applicable to the processing of unde-
sirable particulate material along with dredged sediments.
Utilization of the cartridge water filter is limited in
this application because of operational difficulties en-
countered while using it on slurries with high suspended
solids contents, even though it did produce some removal
of the simulated hazardous materials and the latex paint
tested.
36
-------
SECTION VII
CONCEPTUAL PORTABLE SYSTEM
GENERAL CONSIDERATIONS
The experience gained during the field demonstration was
utilized to develop a concept for a system which could be
utilized to remove and process hazardous materials spills
which had settled to the bottoms of water bodies. The
basic criteria which were followed in defining this system
were:
1. The system had to be portable, preferably to
fit and be transported on one or more semi-
trailers.
2. The system had to have the capability to be
easily and rapidly set up and disassembled.
3. The components of the system had to be reliable
with the minimum possible chance of breakdown
or breakage during processing.
4. Maintenance should be simple and preferably
be performed while the system was on line with
a minimum of hazard to personnel.
5. Capability should be present to process a wide
range of anticipated hazardous materials.
6. Capital and operating costs should be reason-
able.
7. The system had to have the capability of pro-
cessing the full 1500 gpm flow from the MUD
CAT at the expected solids loadings rates.
37
-------
CONCEPTUAL SYSTEM DESCRIPTION
Overall System
After the data from the field demonstration were analyzed,
additional data were reviewed for possible application to
a portable hazardous materials processing system. These
data consisted of manufacturer's literature, published re-
ports, discussions with equipment manufacturer's represent-
atives, and previous experience with and analysis of equipment
which might be applicable for use in the processing system.
The requirements of-the system were balanced with the avail-
able state-of-the-art equipment and possible modifications
or refinements to the equipment which were deemed feasible.
Brief descriptions of alternative pieces of equipment which
were considered for use in the separation system but not
utilized are contained in Appendix C. Figure 3 is a
schematic of the overall conceptual system for the removal
and processing of hazardous materials from pond bottoms. It
has been assumed that the MUD CAT dredge will be utilized
for the removal operation. The dredge proved efficient in
removing materials from a pond bottom as well as providing
a minimum of contamination to the surrounding water, even
under simulated failure conditions.
Initial Separation
From the results of the field demonstration and the sub-
sequent review of additional data, it was apparent that
initial separation of dredged solids and hazardous materials
could best be accomplished by some form of settling basin.
The elevated bins used in the field demonstration were judged
to be too cumbersome in terms of erection and solids unload-
ing, so that an alternative settling device was used in the
conceptual system.
38
-------
Removal System
MUD CAT Dredge
Initial Separation
Portable Scalping-Classifying
Tank and Spiral Classifiers
CO
vo
Removed Solids
Secondary Separation
Uni-Flow Filter
Backflush Sludge
-O
Final Separation
Inclined Tube Settler
-jCoagulant Feeder
Removed Solids Effluent
Removed Solids
Return
Water
to Pond
FIGURE 3. Schematic of Conceptual System
-------
The equipment for the initial separation phase of the con-
ceptual system consists of a portable hydraulic scalping-
classifying tank combined with a spiral classifier. Basically,
the scalping-classifyfng tank is a metal tank which is used
in the sand and gravel processing industry to hydraulically
separate sand and gravel from slurries, and to automatically
meter the release of solids to collecting and blending flumes.
The surface area of the tank determines the size particles
that will be removed as a function of flow rate.
Scalping-classifying tanks have V-shaped bottoms to collect
the settled solids and are equipped with valves on their
bottoms which discharge the solids. Motor-driven vanes sense
the level of solids in the bottom of the tank and automat-
ically open the valves as the solids accumulate. The solids
discharged through the valves drop into flumes which transfer
the solids to spiral classifiers.
Spiral classifiers, also called screw classifiers or sand
screws, are basically rectangular tanks with parallel sides,
a vertical wall at one end, and a sloping bottom which ex-
tends to a height above the top of the other end wall. A
rotating screw which operates on the incline conveys the
settled solids up the sloped bottom and deposits them out-
side the tank.
Figure 4 shows a portable scalping-classifying tank combined
with spiral classifiers. For the hazardous materials process-
ing system, the tank would have a water surface of 40 ft x
10 ft. Two spiral classifiers supplied with the unit each
have a screw diameter of 44 in. and a length of 32 ft.
40
-------
FIGURE 4. Portable Seal ping-Classifying Tank Combined
With Spiral Classifiers
-------
Secondary Separation
The overflow from the seal ping-classifying tank will go to
the secondary separation portion of the system where the
fine-grained materials (less than 74 microns in diameter)
will be removed. In the conceptual system, hydrocyclones
or cartridge filters will not be used. Hydrocyclones are
most effective for removing sand size (74 micron) particles
or larger. Because of operational and maintenance problems
encountered with the cartridge filter unit during the pro-
cessing of dredged slurries, this equipment was also deleted
from the conceptual system.
The most promising piece of equipment for removing fine-
grained material from a dredged slurry and returning a high
quality water to the pond still appears to be some type of
Uni-Flow filter. Experiments with five-inch diameter hoses
(Ref. 1) showed that they would be better than one-inch
hoses for this application. Mainly, fewer problems with hose
blockage were encountered with the larger diameter hoses.
The hoses will be constructed of a polypropylene fabric and
have wire cages on both the inside and outside of the hoses.
The wire cages on the inside of the hose prevent the collapse.
of the hose during the draining cycle, thus producing a more
effective cleaning of the hose. Wire cages on the outside of
the hoses prevent excessive bowing of the hoses during oper-
ation of the filter. This enables the Uni-Flow filter to be
operated at a higher pressure and thus a higher flow rate.
The influent would enter through the bottom of the hoses.
Drained solids would fall into a collection trough beneath
the unit. Coagulants will be added to the backflush sludge
from the Uni-Flow filter and the effluent from this process
will be recycled back into the system for final solids removal.
42
-------
Final Separation
An inclined tube settler will be used as a final solids
separation step in the portable system. This unit was in-
cluded in the system to ensure that water of the highest
quality is returned to the pond. Typically, the Uni-Flow
filter has an effluent which averages a few hundred mg/1
of suspended solids. An inclined tube settler would be
ideal as a downstream addition after the Uni-Flow filter
since settlers are used to clarify wastewater which usually
have less than 1500 mg/1 of suspended solids. The settler
would also serve as insurance should a Uni-Flow hose burst
and release the trapped hazardous materials into the effluent
before the hose can be turned off.
Inclined tube settlers are basically composed of a bank of
inclined tubes which may be circular, hexagonal, square,
rectangular, or chevron-shaped in cross section. Waste-
water influents flowing up through the tubes tend to drop
their suspended solids loads due to the force of gravity on
the suspended particles. The steep inclination of the tubes
causes the settled sludge to counterflow along the side of
the tubes after it accumulates. It then falls into a sedi-
ment storage sump below the tube assembly.
In the conceptual system a coagulant will be added to the
influent to the inclined tube settler. Systems employing
coagulation in conjunction with an inclined tube settler
can remove particles six microns in diameter or smaller.
Typical flow rates through inclined tube settlers are on the
order of three to five gpm per square foot of tube cross
section.
43
-------
EQUIPMENT SIZE
Exact sizing of the conceptual portable system would depend
upon the grain size distribution of the suspended solids
which are present in the dredged slurry. In order to arrive
at an approximate equipment size, an influent grain size
distribution as shown in Figure 5 was assumed. This grain
size distribution might be typical of many bottom sediments
of rivers and ponds and was chosen to test the removal sys-
tem's efficiency in removing the more critical finer par-
ticles. Fifty percent of the solids in the distribution
are finer than sand size. Following are the parameters used
in sizing of the equipment for the conceptual system:
System inflow: 1500 gpm
Grain size distribution of solids: Figure 5
Specific gravity of solids: 2.60
Inflow suspended solids concentration: 20%
Initial Separation
A portable scalping-classifying tank combined with spiral
classifiers which can handle a 1500 gpm flow rate is avail-
able as an off-the-shelf item (Ref. 3). Such a tank has a
water surface area of 400 square feet and is capable of re-
moving particles down to about 54 microns in size at a 1500
gpm flow rate. This means that 63 percent of the solids in
the incoming dredged slurry will be removed in the initial
separation phase. The tanks and spiral classifiers should
be able to attain an underflow solids concentration of 50
percent. Table 9 shows the mass balance of the initial
separation phase.
44
-------
cn
100
90
80
70
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U.S. STANDARD SIEVE OPENING IN INCHES U.S. STANDARD SIEVE NUMBERS HYDROMETER
6 4 3 2 IVi 1 % 14 % 3 4 6 8 1O 14 16 20 30 40 50 70 100140 200
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II
\
^
\
\
\
V.
\
\
V
N
Ts
0.05 0.01
^
*^
•^
1
0.005
-
T,
0.0
SILT OR CLAY
o
10
20
30 £
0
5
40 1
a:
Ul
50 £
O
u
60 5
111
-------
Table 9. MASS BALANCE OF INITIAL
SEPARATION PHASE
Inflow (1500 gpm 9 20% solids)
Solids: 2,850 Ib/min
Water : 11,400 Ib/min
Total Slurry: 14,250 Ib/min
Underflow (50% solids)
Solids: 1,796 Ib/min
Water : 1 ,796 Ib/min
Total Slurry: 3,592 Ib/min
Overflow (1207 qpm @ 9.9% solids)
Solids: 1,054 Ib/min
Water : 9.604 Ib/min
Total Slurry: 10,658 Ib/min
46
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Secondary Separation
The Uni-Flow filter used for secondary separation will con-
sist of 10-foot-long, 5-inch diameter hoses with wire cages
on the inside and outside. Using these hoses at the solids
loadings expected, the Uni-Flow filter should be able to
process the slurry at an average rate of 0.13 gpm per square
foot. This would require a minimum of 715 hoses to process
the expected 1207 gpm expected to enter the secondary sep-
aration phase. Figure 6 shows a plan view of how these hoses
would be arranged for the Uni-Flow filter in the conceptual
system.
A coagulant will be added to the sludge which is drained
from the Uni-Flow hoses. The solids settled from the sludge
would then be disposed of and the supernatant would be re-
cycled to be treated in the final separation phase.
Final Separation
The final separation phase, in the form of an inclined tube
settler, is included as added insurance for a clean system
effluent. Coagulant will be added to the influent to the
inclined tube settler in order to improve its performance.
Tests on the Uni-Flow filter indicate that effluents from
this piece of equipment can sometimes be expected to reach
about 1500 mg/1 of suspended solids. This Is true especially
if a hose breakage occurs, or immediately after a backflush
or hose draining cycle when the hose is relatively clean and
a coating of sediment has not built up.
Inclined tube settlers are generally used to clarify waste-
water influents which have under 1500 mg/1 of suspended
solids. Typical flow rates through the settlers are on the
47
-------
8'
00
1.5'
2'
40.5
12 banks of hoses @ 64 hoses/bank = 768 hoses
FIGURE 6. Plan View of Uni-Flow Filter for Conceptual System
SCALE: 1" = 5
-------
p
order of 3 to 5 gpm/ft^ and can remove particles down to the
6 micron or smaller range when coagulation is employed. An 8
ft x 38 ft settler would provide 304 sq ft of area and would
thus have a flow rate on the order of 4 gpm/ft2 at 1200 gpm.
Such a unit would fit on a standard semitrailer bed.
Auxiliary Equipment
The conceptual removal and separation system will require a
total of five semitrailers for transport of the complete
1500 gpm system, including auxiliary equipment. Breakdown
of the transportation requirements is as follows:
(1) Removal System - 1 custom semitrailer to
hold MUD CAT dredge and
pipe
(2) Initial Separation - 1 portable scalping-
classifying tank and
spiral classifiers,
size of one semitrailer
(3) Secondary Separation - 1 Uni-Flow filter on
low boy trailer
(4) Final Separation - 1 inclined tube settler
on standard size semi-
trailer
(5) Auxiliary Equipment - 2 pumps, piping, coagulant
feeder, etc. to fit on one
semitrailer
COST
Table 10 contains the estimated initial cost of the portable
separation system which can handle an initial inflow of 1500
gpm. Figure 7 shows approximate portable scalper and
49
-------
Table 10. ESTIMATED INITIAL COST OF 1500 RPM
PORTABLE SEPARATION SYSTEM
Quantity Item Cost
1 Portable scalping-classifying tank
combined with spiral classifiers (Figure 7) $84,000
1 Uni-Flow filter: 768, 5" diameter, woven
polypropylene hoses with wire cages on the
inside and outside 20,000
1 Inclined tube settler: 304 sq ft @
$25/sq ft 7,600
Auxiliary Equipment: coagulant feeder,
piping, 2 pumps 2,100
1 Low boy trailer 12,000
2 Semitrailers 24,000
Total cost $149,700
50
-------
100,000 —
90,000
80,000 —
70,000 —
60,000
50,000 —
200
600
FIGURE 7. Portable Scalper and Classifier Costs
(Reference 4)
51
-------
clarifier costs. The major initial cost of the separation
system arises from the portable sealping-classifying tank
and spiral classifiers. In order to defray some of these
costs, these units are sometimes available on a rental
basis. However, the decreased costs during rental must be
offset by the decreased responsiveness of the system if no
rental units are available at the time of need.
The second major cost item is that of the trailers to trans-
port the processing system. Table 10 reflects the approxi-
mate cost of new trailers. Used trailers in good condition
can usually be purchased for about one quarter of the cost
of a new trailer. Trailers can also be hired on an as
needed basis, but again the decreased costs during rental
must be offset by the decreased responsiveness of the sys-
tem if no trailers are available at the time of need.
52
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SECTION VIII
REFERENCES
1. Nawrocki, Michael A., Demonstration of the Separation
and Disposal of Concentrated Sediments, U.S. Environ-
mental Protection Agency, Document Mo. EPA 660/2-74-072,
June 1974, 77 pp.
2. American Public Health Association, Standard Methods for
the Examination of Water and Wastewater, 13th Edition,
Washington, D.C. , 1971 .
3. Eagle Iron Works, Eagle Water Scalping-CIassifying Tanks,
Dialsplit ® and Autospec ® Controls. General Catalog
Section "B", Des Moines, Iowa, August 1971, 24 pp.
4. Mallory, Charles W., and M.A. Nawrocki, Containment Area
Facility Concepts for Dredged Material Separation. Prying.
and Rehandling, U.S. Army Engineer Waterways Experiment
Station, Contract Report D-74-6, October 1974, 236 pp.
53
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APPENDIX A
ILLUSTRATIONS OF REMOVAL AND PROCESSING EQUIPMENT
-^«. •
9
ai!
. • ~
~«^.
FIGURE A-l . Overall View of the MUD CAT Dredge
FIGURE A-2. Close-up View of the MUD CAT Auger
54
-------
FIGURE A-3. The Two Elevated Bins
FIGURE A-4. Hydrocyclone Unit
55
-------
FIGURE A-5. Cartridge Filter Unit
FIGURE A-6. Uni-Flow Filter
56
-------
en
Backflush
Disposal
Basin
Processi ng
System
FIGURE A-7. Layout of Demonstration Site (not to scale)
-------
APPENDIX B
DETAILED DATA AND COMPUTATIONS
Table B-l. SUMMARY OF MUD CAT PUMPING RATE ANALYSES
Remarks
Flow Rate
Flow Rate Calculation Method (gpm)
MUD CAT pump rating curves
and total friction head in
piping as set up in field 2000
Sharp-edged rectangular weir
formula-overflow between first
and second bin 1740
Time to fill the volume of the
first bin 1660
Pipe discharge exit formula 1800
Time to fill volume or pipe
between MUD CAT and dis-
charge to first bin 1920
Average 1820
NOTE: The first two flow rates are probably the most accurate
since they are the result of exact measurements and fairly
well-defined formulae. However, since no valid reason could
be found for invalidating any of the results, the average
pumping rate of 1820 gpm was used in all calculations. It
should be noted, also, that this estimate of flow can only
be expected to be, at best, within +_ 10 percent of the actual
flow due to the inherent inaccuracies in the formulae.
Time measurement
is approximate.
Time measurement
is approximate.
58
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TABLE B-2. VALUES FOR CALCULATING AMOUNT OF SIMULATED HAZARDOUS MATERIAL IN BINS
Volume of Sediment
Test
Material
Iron Powder
Glass Beads
tn
Iron Filings
Coal
Bin
#1
#2
#1
#2
#1
#2
#1
12
Depth of
Sediment
(ft)
4.5
2.5
3.5
1.5
3.5
1.5
3.5
1.5
From Lead-in
Area
(ft3)
6.68
1.14
11 .85
1 .18
5.89
0.59
7.60
0.76
From Entire
Dredgin?
71.26
12.18
33.10
3.31
33.10
3.31
33.10
3.31
From Test
Area
(ft3)
64.58
11 .04
21 .25
2.13
27.21
2.72
25.50
2.55
Weight of
Test Material
210.36
12.49
0.34
0.05
*
*
447.27
3.99
Specific Gravity
of Bin
Residue
2.70
2.61
2.59
2.61
*
2.51
2.51
2.51
* Sample believed to be nonrepresentative.
-------
Table B-3. TOTAL SIMULATED HAZARDOUS
MATERIALS BALANCE
Unit
Test Material (Total Ib removed)
Glass Iron Iron
Beads Filings Powder* Coal*
Elevated bins
Bypass
Hydrocyclones
Cartridge Filters
Uni-Flow
Subtotal:
113.4
339.4
17.3
1.2
1.2
472.5
526.4
40.6
6.7
0.6
0.7
575.0
130.2**
84.6**
2.1
1 .1
1.7
219.7
97.0**
42.2**
3.7
2.0
1.0
145.9
Pounds in outfall
(return water to pond) <0.1
Pounds left on bottom <0.1
0.4
8.0
2.1
Total weight accounted
for 472.5
Total weight placed on
bottom 500.0
Percent material
accounted for 94.5
575.4
500.0
115.1
227.7
800.0
28.5
148.0
500.0
29.6
*Because of inaccuracies in measuring the amount of iron
powder and coal in the bypass, and the fact that these two
simulated hazardous materials were nonuniformly distributed
in the bin sediments, the values shown for the pounds re-
moved by the elevated bins and the bypass may not reflect
the true values.
** Imputed value.
60
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Table B-4. SUMMARY OF EFFLUENT CONCENTRATIONS
(mq/1)
Component
MUD CAT Discharge
Elevated Bins
Demco
Crall
Uni-Flow (Return
Water to Pond)
Average
128,460
82,520
53,800
40,860
750
Maximum*
160,500
140,500
103,040
94,430
1,770
Minimum
107,030
55,830
31,400
22,740
230
* All of the maximum values come from one test, the test for re-
moval of paint.
61
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Table B-5. BACKFLUSH CONCENTRATIONS
Component
Demco
Crall
Uni-Flow
Suspended Solids (mq/1 )
AVG.
56,060
103,660
84, 640
MIN.
8,570
37,680
25,900
MAX.
106,250
284,580
191,600
NOTE: The various units were manually backflushed at the
end of the test period. If left to backflush in the
automatic mode, the concentrations of suspended solids
in the backflush would have been different. Normally,
the various units were set 'to backflush on a regular
basis which usually corresponded to the time the
backpressure in the unit built-up to near a maximum
permissible level. Thus, the backflush concentration
values in these tests do not necessarily reflect the
maximum increase in the solids concentration in the
backflush as compared to the concentration in the
influent which can be achieved by the unit. On a
continuous operation basis the advantage of this system
would be in being able to isolate and subsequently
dispose of most of the hazardous material in the
backflushes of the various units in concentrated
form.
-------
Table B-6.
PERCENTAGES OF SIMULATED HAZARDOUS
MATERIAL (S.H.M.) IN THE EFFLUENTS
OF THE PROCESSING SYSTEM ELEMENTS
Sampling Point
Test Material
Iron Powder Glass Beads Iron Filings Coal
Percent
S.H.M. in
Effluent
Percent
S.H.M.
in Residue
#5
#1
#2
#3
#4
Bin 1
Bin 2
3.70
3.30
2.90
2.70
0.05
2.0
0.7
4.87
4.59
1.60
1.10
0.08
0.010
0.014
11.80
1.63
0.41
0.37
0.05
75.8
21.8
2.30
2.00
1.00
0.50
0.05
11.2
1.0
Sampling Point Key
#5 = MUD CAT discharge into elevated bins
#1 = Bin effluent - Influent to Demco Centrifugal Separator unit
(hydrocyclones)
#2 = Demco effluent - Influent to Crall cartridge filters
#3 = Crall effluent - Influent to Uni-Flow bag-type filter
#4 = Uni-Flow effluent (return water to pond)
63
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EXAMPLE CALCULATION
To compute the amount of simulated hazardous material (S.H.M.) in the influent to
the hydrolocyclones (effluent from the bins) for the Iron Powder test, the
following data are used:
(1) (2) (3) (4) (5)
Sampling Dredged Slurrv %S.H.M. S.H.M. Soil
Point Concen. (mg/1) in Effluent Solids Concen. (mg/1) Concen. (mg/1)
(from Table 5) (from Table B-6) (Col .3 x Col .2) (Col .2 - Col .4)
#1 61,320 3.30 2024 59,296
Assume mg/1 = ppm.
The total pounds of S.H.M. passing the sampling point during the entire test can
then be computed by:
Total Ib =[flow (gpm)] x [wt. of water (Ib/gal) x specific gravity of slurry] x
[S.H.M. concentration] x [duration of test (min)]
Therefore, Total Ib = [100 gpm] x [8.35 Ib/gal x 1.04] x [.002024] x [2.8] = 4.9 Ib
-------
APPENDIX C
ALTERNATIVE EQUIPMENT
The following section contains brief descriptions of
additional alternative pieces of equipment that were
investigated for their possible use in the conceptual
portable processing system but were not included in
the final system.
65
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(1) ELECTRO/MEDIA, Hi-Velocity, and Plastic Media Filters,
Hayward Filter Company, Santa Ana, California. Fil-
ters produced by this company are normally used for
water clarification and wastewater treatment. They
filter water by passing it through various media
such as sand, garnet, coal, plastic, and aluminum-
bearing granules. Turbidity removals of 95 to 99
percent have been reported for these filters. Their
drawbacks for portable service include their large
size (requiring over four times the space of the Crall
filters) and high weight. Flow rates for the three
Hayward filters range from 15 to 30 gpm per square
foot of fjlter area.
(2) Rotostrainer ®, Hydrocyclonic Corporation, Lake Bluff,
„.„. . .,„ „„„»,.,„. system of solids de-
watering has advantages over other screening methods.
The size, 2(29" x 72"), takes between 1/2 to 1/3 the
space as other methods. Also, it is self-cleaning
with the dewatering solids from raw sewage producing
a dry weight of 25%. The cost for a 1500 gpm unit is
approximately $10,000, with maintenance costs relatively
low. One major drawback with the Rotostrainer ® is
the 250-micron final particle retention size at the
required flow rate which is well above the needed
requirements.
(3) Adams PORO-EDGE Automatic Water Strainers, R.P. Adams
Company, Inc., Buffalo, New York. These filters are
used in general service for water clarification and
process water treatment. Again, their main use is
in permanent installations. The standard unit comes
66
-------
equipped with openings to strain particles in the 250-
micron or larger range, although finer and larger
opening sizes are available. The PORO-EDGE Automatic
Water Strainer might be a good piece of equipment for
use in the initial solids removal step of the full
capacity 1500 gpm system if the absence of large rocks
could be guaranteed. The cost of such a strainer
would be on the order or $2500.
(4) Matz Micro-Solids Separator, Matz Corporation, Holyoke,
Massachusetts. This is a relatively new piece of
commercially available equipment. Limited data are
available on its performance characteristics. How-
ever, some tests show suspended solids removal rates
on the order of 83 percent for initial concentrations
in the 130 ppm range. The equipment backwash cycle
requires a greater number of moving parts than other
water clarifiers, thus leading to a possible increase
in maintenance and downtime, important considerations
in field installations.
(5) Flat Bed Pressure Filter and Hydro-Vac Filter, Hydro-
mation Engineering Company, Livonia, Michigan. These
filters are used primarily in industrial filtration
of waste streams from metal working operations and
washing systems, and chemical process liquors. These
fabric filters are used exclusively in permanent in-
stallations. Their rated filtration removal of par-
ticles down to one micron in size is excellent although
their large size (requiring approximately 200 square
feet of area for only a 500 gpm unit) and bulky shape
make them unwieldy for portable field use. Cost of a
500 gpm unit (approximately $38,000) is also high
compared to other available equipment.
67
-------
(6) Akin to the above Hydro-Vac and Flat Bed Pressure
Filters are a number of standard rotary drum or mov-
ing belt filters. These filters utilize fabric to
screen the inlet process water. Very fine filtration
can be achieved by using precoat materials on the
fabric or by utilizing new types of fabric being
developed. Flow rates on the order of 1 to 10 gpm
per square foot of filter area are commonly achieved.
The cost of a 500 gpm unit would be on the order of
$30,000 to $40,000. The equipment is bulky and not
suited for portable field application. Manufacturers
of such filters include Dorr-Oliver of Stanford,
Connecticut; Impco of Nashua, New Hampshire; Komline-
Sanderson of Wilmington, Delaware; and Eimco of Salt
Lake City, Utah.
(7) Continuous Solid Bowl Centrifugal, Bird Machine
Company, South Walpole, Massachusetts. Centrifuges
of this type employ a rotating drum to concentrate
the solids from a solids-liquid mixture. Small units
of this type would lend themselves to easy portabil-
ity. For example, a solid bowl centrifugal which
could handle a flow rate of 300 gpm would only occupy
a 3 foot by 12 foot space and could be readily mounted
on a trailer. Rejected solids from these units can be
expected to be approximately 20 to 45 percent solids
by weight. The cost of these units, however, makes
them a less attractive alternative. Selling price
for a 300 gpm unit, less auxiliaries, would be approx-
imately $75,000. In addition, the machine would re-
quire a 200 horsepower drive motor, either electrical
or diesel.
(8) Dewatering screens. These are basically screens of
a specific mesh size set at an angle. A slurry flows
68
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over the surface, with water flowing through the
screen with the solids being collected at the lower
end of the screen. These units are used in the pulp
and paper industry, for fruit and vegetable processing,
in sand and gravel processing, and in the mining of
iron and copper ore. They have flow rates of between
30 to 500 gpm per screen, depending upon mesh size
of the screens. Mesh sizes range from 2.38 mm to
44 microns. They are made for permanent installation,
but because of their size they could be used for
portable applications.
(9) Vibrating screens. These screens are similar to
normal dewatering screens except for the fact that
they are vibrated during processing. They are
normally used in sand and gravel processing to re-
move particles greater than about one-tenth of an
inch in diameter. Small size screens, down to 400
mesh, can be used, but the flow rate drops consider-
ably. Thus, more screens would be required for a
high flow rate. Manufacturers of vibrating screens
include: Smith Engineering Works, Wisconsin; Denver
Equipment Division of Joy Manufacturing Co., Colorado;
Kribs Engineers, California, Derrick Manufacturing
Corp., New York; and SWECO, Inc., California.
69
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT
PORT NO.
EPA-600/2-76-245
2.
3. RECIPIENT'S \CCESSIOI*NO.
4. TITLE AND SUBTITLE
REMOVAL AND SEPARATION OF SPILLED HAZARDOUS
MATERIALS FROM IMPOUNDMENT BOTTOMS
5. REPORT DATE
September 1976 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Michael A. Nawrockl
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Hittman Associates, Inc.
9190 Red Branch Road
Columbia, Maryland 21043
10. PROGRAM ELEMENT NO.
1BB610 03-03-09A-02
11. CONTRACT/GRANT NO.
68-03-0304
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory-Cin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final; June 1973 - Oct. 1974
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A demonstration was conducted of a system for removing spilled hazardous materials
from pond bottoms and separating the hazardous materials and suspended solids from
the resulting dredged slurry. The removal system consisted of a MUD CAT dredge.
The processing system consisted of a pair of elevated clarifier bins in series, a
bank of hydrocyclones, a cartridge filter unit, and a Uni-flow bag-type fabric
filter.
The MUD CAT proved efficient in removing particulate simulated hazardous materials
from the pond bottom without imparting a substantial amount of turbidity to the
water. The processing system was effective in removing particulate simulated
hazardous materials from the processing stream and also in removing most of the
pigment from a latex paint which was tested.
A conceptual portable system for processing at 1500 gpm was prepared. This system
consisted of a scalping-classifying tank combined with spiral classifiers, Uni-Flow
filter, and an inclined tube settler.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
*Dredging
hazardous Materials
*Filtering Systems
*Separation Techniques
*Pollution Abatement
Impoundments
Water Quality Control
Slurries
Waste Disposal
Hazardous Materials
Removal and Separation
Portable Processing
Systems
13/b
8. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
78
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
U. S. GOVE«NMENT MINTING OFflCE: 1977-757-056/5551 Region No. 5-11
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